In recent years, there has been an image pickup apparatus in which a microlens array comprised of micro lenses formed in a grid pattern is disposed between a taking lens and an image pickup device, and information on the intensity distribution and incidence directions of light passing through the micro lenses is obtained as pixel signals when a still image and a moving image are taken (see NPL (Non Patent Literature) 1). The image pickup apparatus described in NPL 1 obtains pixel signals based on light having passed through the micro lenses, and generates image data based on the pixel signals. The obtained pixel signals and the generated image data are stored in, for example, the image pickup apparatus. The image pickup apparatus described in NPL 1 also has a refocusing function of changing a focal position of generated image data to an arbitrary position based on the stored pixel signals.